The invention relates to an exposure arrangement for the production of masks, using a computer-aided design system. The arrangement comprises a cathode-ray tube which forms an image of the mask on the screen of the tube, and an optical system which projects the image of the mask onto a substrate which is to be exposed.
Such an arrangement is used in the manufacture of semiconductor devices, in the thin-film and thick-film technique, in production processes in the photographic industry etc.
Such an invention is known from Japanese Patent Application 58.18923 which describes an arrangement consisting of a cathode ray tube having a glass screen which is provided with a phosphor layer in front of which there is positioned an array of optical fibers which catches the light rays issuing from the screen and conducts them in the form of parallel beams. In this way, a substrate located at one end of the array of optical fibers is exposed by light issuing from the screen on which appears the geometrical pattern of the mask produced by means of a computer-aided design system. Apparently, this device is designed to provide the most direct way of utilizing the mask image as it appears on the display console of the computer-aided design system.
However, the arrangement has some disadvantages. First, the magnification of the system can only be equal to 1, the dimensions of the projected image being equal to the dimensions of the image of the screen. Second, as the screen of the tube and the array of optical fibers are made of glass, the spectrum emitted by the photosensitive layer can only be situated in the visible spectrum. Consequently, the final definition of the projected image is limited by the large wavelength of light. Moreover, as the cathode-ray tube used is of a standard type, i.e. it is adapted to the human eyesight, it exhibits a low brightness which is unsuitable for an exposure arrangement and, consequently, leads to long exposure times and an increase in reconstruction errors.